Aug 19 2004
The power required by mobile phones in rural areas where base stations are sparse is significantly higher than in urban areas where base stations are plentiful, concludes research in Occupational and Environmental Medicine. This should be taken into account when considering the potential impact of mobile phone use on health, say the authors.
The research team recorded the power levels (radiofrequency) of mobile phones used on the same network during one week in four different areas: a rural area comprising small villages and open countryside; a small town; a city suburb; and a city (Stockholm).
They wanted to test whether electromagnetic power is greater when there are large distances between the user and the base station and much less when the distance between base stations and the user is short.
The final data included 230,000 hours of transmission time. Most of the time was in the radiofrequency band of 900 Mhz. There were differences in power levels according to location.
The small town had the lowest proportion of call time at the highest power level. The density of base stations is likely to be lower than that in the city. But the buildings in cities tend to be larger, which weakens the signal, bumping up the power required.
In the rural area, the highest power level was reached half of the time, and the lowest power level was reached just 3% of the time. The highest power level in the city was reached 25% of the time and the lowest 22% of the time.
Although the evidence so far suggests that mobile phone emissions are not harmful to users, the results are not conclusive for use over the long term, say the authors. And the power required by a mobile phone can differ by more than 1000-fold, depending on how and where it is used. It is one of the most important factors in determining the intensity of exposure to electromagnetic fields.
The research is reported in research in Occupational and Environmental Medicine.
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